JP4871864B2 - Non-homogeneous engine components molded by powder metallurgy - Google Patents

Abstract

A connecting rod unitarily formed in a powder metallurgy process provides a non-homogenous structure. The connecting rod has a piston end, a crankshaft end, and an interconnecting shank. The piston end, the crankshaft end, and the interconnecting shank are formed of a structural material.

Description

  The present invention relates to components molded by powder metallurgy and, more particularly, to a method and apparatus for molding components by powder metallurgy.

  Powder metallurgy is a common manufacturing method used to manufacture high quality components used in engines and the like. Powder metallurgy is often used in the manufacture of engine components because it is economical, flexible, and can produce finished parts that require less machining or secondary processing than other component molding methods. Is done. Using powder metallurgy, components can be formed from a wide variety of alloys, composites, and other materials, so that the finished component has the desired properties. Powder metallurgy is suitable for producing parts of a wide range of sizes and shapes. Powder metallurgy is also advantageous because parts with stable dimensions and physical properties can be manufactured with high reliability.

  FIG. 1 shows a process chart of a conventional powder metallurgy component forming process 30. First, metal powder constituting the component is prepared (step 32). Lubricants are often added to metal powders to reduce press wear. The substrate powder is then mixed to form a homogeneous mixture (step 34). What is completed is a homogeneous alloy of metal powder, which is a constituent component.

  Next, the mixed powder is filled in a mold or a mold (step 36). Closing the mold creates an internal cavity whose shape is somewhat similar to the final part. The powder is compressed in a mold (step 38) into a so-called “green part”. Usually, compaction is performed at room temperature, for example, by applying a pressure of 30 to 50 tons per square inch (step 38). The green part is also called “green compact”, but when it is extruded from the mold, it has a desired size and shape suitable for the next step. After compaction (step 38), the green part has sufficient strength for subsequent processing.

  The green part is subjected to a sintering process (step 40). The parts after sintering (step 40) are subjected to various secondary processes according to the purpose of use (step 42), and a finished part is completed (step 44).

  In general, sintering (step 40) involves exposing the green part to a temperature of, for example, 70-90% of the melting point of its constituent metal or alloy. By controlling the temperature, time, and atmosphere variables in the furnace, a sintered part with improved strength is produced by bonding or alloying metal particles. The sintering process (step 40) includes three basic steps performed in the sintering furnace: degreasing (step 46), sintering (step 48), and cooling (step 50). Usually, the above process is performed using a continuous sintering furnace. The degreasing chamber is used to volatilize the lubricant used for green part molding (step 46). The high greenhouse performs the actual sintering (step 48). The cooling chamber cools the parts prior to handling (step 50).

  The part taken out of the sintering furnace (step 40) after cooling (step 50) is considered a finished product. Alternatively, the part may undergo one or more secondary processes (step 42). Secondary processing includes, for example, component re-pressing (forging) (step 52), machining (step 54), barrel polishing (step 56), and joining the component to another component that is part of the overall assembly. Processing (step 58) is included. Secondary processing (step 42) may include impregnating the part with an oil or lubricant (step 60) to provide automatic lubrication properties. The sintered component may be heat treated (step 62) to give the component certain characteristics and properties, such as strength. One skilled in the art will appreciate that other secondary processing may be performed. Each secondary processing (step 42) may be performed alone or in combination with other secondary processing. When all secondary processing has been performed (step 42), the component or part is complete (step 44).

  US Pat. Nos. 6,055,884, 5,551,782, and 5,353,500 each disclose a connecting rod for use in an internal combustion engine. .

  FIG. 2 shows internal details of a conventional internal combustion engine in order to explain how the connecting rod 64 is used. The connecting rod 64 is connected to the piston 66 and the crankshaft 74 so as to be axially rotatable. The connecting rod 64 has a larger end or a crank side end 76 connected to the crankshaft 74. The larger end 76 of the rod 64 receives a shaft portion (“crank pin”) 78 of the crankshaft 74. The connecting rod 64 further has a smaller end of the rod 64 or a piston side end 70 connected to the piston 66. A pin (“wrist pin”) 68 is used to allow rotation between the smaller end 70 of the connecting rod 64 and the piston 66.

  3 to 5 show a conventional connecting rod 64 manufactured according to a conventional method. The connecting rod 64 includes a piston side end portion 70, a crankshaft side end portion 76, and a body portion 80. The body 80 is often provided with one or more recessed portions for weight reduction. The crankshaft side end 76 includes a large eye 77 for receiving a crankpin 78. The crankshaft side end 76 includes a crank bearing 84 to minimize wear and friction due to the rotational movement of the shaft 78 within the large eye 77. The bearing 84 includes a bearing material 88, an outer material seating surface 89, and an inner bearing surface 86. As will be appreciated by those skilled in the art, the crank bearing 84 forms a fluid bearing when lubricating oil is supplied between the crank pin 78 and the inner bearing surface 86.

  The piston end 70 of the connecting rod 64 includes a small eye 81 for receiving a wrist pin 68. The small eye 81 is provided with a bushing 90 for reducing friction and wear caused by rotational movement during operation. The bushing 90 includes a separate or separate bearing material 92, an inner bearing contact surface 94, and an outer bearing seating surface 96.

  The connecting rod 64 is usually made of steel or an aluminum alloy. At present, a titanium alloy is also used for the connecting rod 64. The bushing 90 is typically made of bronze.

  Crank bearing 84 and bushing 90 are conventionally provided on connecting rod 64 as part of the secondary manufacturing and assembly process. Bearing 84 and bushing 90 are each typically molded as part of their own separate manufacturing process and then joined to connecting rod 64 as a separate manufacturing or assembly process. As the number of processes increases, the time, tools, and labor costs for the manufacturing process increase. An ongoing challenge for all manufacturing is cost reduction.

  Accordingly, there is a need to provide connecting rods for engines that reduce the number of manufacturing steps, tools, parts, and labor costs.

  The connecting rod includes a heterogeneous structure formed into a single body by a powder metallurgy process using at least two different metal components that provide different properties at distinct locations in the structure.

  FIG. 6 shows a process for manufacturing a component made of non-homogeneous powder metallurgy, including a connecting rod. In step 106, one or more kinds of metal powders are introduced into the mold. Two, three, or more types of metal powders may be introduced simultaneously (in parallel), at different times (sequentially), or any combination of the above times. Various metal powders may be a mixture of various components. The metal powder is mixed prior to introduction unless it is desirable for non-homogeneous results. At step 108, the powder in the mold is pressed to form a green part. In step 110, the green part is sintered. One or more secondary processes such as forging, machining, heat treatment, finishing, etc. may be performed at step 112. As those skilled in the art will appreciate, additional lamination and / or processing steps of the powdered metal can be performed without departing from the spirit and scope of the present invention.

  One embodiment of the raw component molding apparatus 120 is shown in FIG. The green part forming apparatus 120 is generally called a feed shoe apparatus 120. The feed shoe device 120 generally includes a powder filling container 122 operable by an actuator cylinder 134, an upper punch 140, a lower punch 142, and a powder hopper 148. More specifically, the first container 122 is firmly connected to the second container 126 by one or more connecting members 138. The second container 126 is connected to the actuator cylinder 134 via the piston 136. The actuator cylinder 134 is a hydraulic or pneumatic cylinder for pushing the piston 136 in or out to guide the first container 124 and the second container 125 in a controlled movement manner. Each container 124, 126 includes a sidewall 125 that defines an internal cavity 124, 128 therein. Side wall 125 has an inclined portion 129 that directs the powder to powder outlet valve 146. The upper openings 127 of the containers 122, 126 are sized to receive the chutes 152, 154 connected to the hoppers 148, 150. The hoppers 148 and 150 receive the first and second powdered metals supplied to the first inner cavity 124 and the second inner cavity 128, respectively. The first chute 152 and the second chute 154 include a flexible tube made to allow linear movement of the first container 122 and the second container 126. Both the first and second containers 122, 126 move linearly by sliding over the bridge member 132. The bridge member 132 and the actuator cylinder 134 are mounted on the mold table 130, respectively.

  A side view of the feed shoe device 120 is shown in FIG. The mold table 130 is provided with one or more locking mechanisms 160. The locking mechanism 160 allows the containers 122 and 126 to be positioned during the filling operation of the mold cavity 144. The locking mechanism 160 may be a magnet or other locking means such as a male / female socket or equivalent.

  The bridging means 132 is slidably disposed on the guide 166. Each guide 166 is further disposed on a rail 168. Each bridge member 132 is provided with an elevating cylinder 162, and the elevating cylinder 162 is formed so that the bridge member 132 can be raised above the guide 166 by extension of the elevating piston 154. As shown in FIG. 2, the actuator cylinder 162 can move the container 122 laterally with respect to the cavity 144 in a state where the first container 122 and the mold cavity 144 are separated. Conveniently, the containers 122, 126 are moved away from the punches 140, 142 so that they do not interfere with the pressing process.

  FIG. 9 shows a top view of the feed shoe device 120. Each container 122, 126 is drawn with a portion broken away to show the interior in detail. The dotted lines on the outer periphery 172 of the mold cavity are shown for illustrative purposes. One or more powder outlets 170 are located on the bottom surface of each container 122, 126. The powder outlet 170 includes a valve 148 for controlling the delivery of powder metal to the mold cavity 144. The outlet 170 is sized to control the relative flow rate through the particular outlet 170 during the filling process. The first container 122 is shown as having one outlet 170. The second container 126 is shown as having three outlets 170 of different sizes. Various polygonal shapes, eccentric shapes, or different sizes can be employed instead of a circular outlet without departing from the scope of the present invention.

  The size and position of the powder outlet 170 is selected to suit the requirements of the predetermined characteristics for the finished part. For example, piston rods for internal combustion engines use bearings as part of the wrist pin assembly. In a conventional method for manufacturing a connecting rod, a separately molded bearing is mounted on a previously molded connecting rod as part of a secondary process. The apparatus and method disclosed herein is advantageous because it provides a precisely positioned powder outlet for molding a bearing integral with a connecting rod.

  The feed shoe device shown in FIG. 9 includes a liquid injection device 174 in addition to the above. The liquid injection device 174 injects liquid into the first internal cavity 124 during the molding process. The inlet to the infusion device 176 is connected to a liquid conduit 178 that supplies the solution. This device includes a solenoid valve such as a solenoid valve with a dead leg volume of zero. Various suitable valves that do not drip can be used without departing from the scope of the present invention. As will be appreciated by those skilled in the art, the second container may be provided with a second liquid injection device to practice the present invention, or may be implemented with a single liquid injection device in communication with both the first and second containers. You can also

  Examples of the solution include an aqueous solution, a lubricant, a surfactant, or an activation solution for washing metal particles in preparation for cold welding. Solutions include any solution that is intended to be miscible in the material or solvent, such as a curing agent. Lubricant injection is performed to reduce wear in the mold cavity of the device.

FIG. 10 shows a valve assembly 148 with a powder outlet 170 for containers 122, 126. The housing surface 182 defines an open position P ₁ and a closed position P ₂ for the powder outlet 170 in cooperation with the slide hole 124. Slide hole 184, the actuator 134 in response to cause linearly translate the containers 122 and 126, to move between positions _{P 1} and _{P 2.} In the open state, the metal powder is free to leave the container and enter the mold cavity. In the closed position, powder transfer to the cavity is prevented. Other methods or devices can be utilized to block the flow of powder from the feed shoe to the mold cavity without departing from the scope of the present invention.

  FIGS. 11 and 12 show an alternative embodiment of an apparatus and method for controlling the flow of metal powder into the cavity 144. A feed tube 186 communicates between the internal cavities 124, 128 of the containers 122, 126 and the mold cavity 144. The feed tube 186 is made of a flexible material such as rubber. The bottom sidewalls of the containers 122, 126 define a channel 188 as shown. In the channel 188, a pinching or picking device 190 is arranged. When the picking device 190 is retracted, that is, not pressing the tube 186, the feeding tube 186 is in the open position as shown in FIG.

  FIG. 12 shows the tube 186 in a closed position where the picking device 190 pressed the side walls of the tube until they touched each other to block the powder flow. The knob device 190 is pushed toward the feed tube 186 by pneumatic control. The channel 188 is supplied with high pressure and presses the picking device 190 against the tube 186. When this high pressure state is removed, the tube 186 reopens due to its inherent elasticity and the powder flows. Mechanical means such as a linkage can be used in place of the pneumatic drive means without departing from the scope of the present invention.

  Methods and apparatus for producing non-homogeneous articles by powder metallurgy are described in FIGS. 6-8 and the associated text. The following description is more focused on the manufacture of connecting rods for internal combustion engines, where the rod has an integral bearing that is integrally molded as part of a single molding process. A first metal powder such as steel is placed in the first hopper 148 and a second metal powder such as bronze is placed in the second hopper 150. The first container 122 is centered on the mold cavity 144 by expanding and contracting the piston 136 of the actuator cylinder 134 as necessary.

  First metal powder is introduced into the first internal cavity 124. A predetermined amount of the first powder is filled into the mold or mold cavity 144 through the powder outlet 170. The flow of the first powder is stopped by valve 148 at the powder outlet 170. The piston 136 is extended until the center of the second container 126 is over the mold cavity 144. The powder outlet 170 is not centered on the mold cavity, so that the second powder can be deposited at an individual position where an integral bearing is to be formed. So convenient. The mold cavity 144 is filled with a predetermined amount of the second powder. The first and second powder filling steps are repeated until the cavity 144 is filled with a sufficient amount of metal powder to form the finished part.

  The piston 136 is retracted until the first container 122 is in a position where it is out of the punches on the upper side 140 and the lower side 142. Once the clearance is established, it is advantageous because the powder in the mold cavity 144 is pressed and the green part is molded. The green part is placed in a sintering furnace and then cooled. The cooled sintered connecting rod is machined to final tolerance. Secondary processing such as forging, carburizing, nitriding, or grinding the bearing retainer from the remainder can be performed without departing from the scope of the present invention. Since integral bearings are provided during the molding process, separate or separate bearings are provided at both the piston end (smaller end) and the crank end (larger end) of the rod, It is not necessary to provide it as part of the secondary processing. When other secondary processing is completed, a finished connecting rod is obtained.

  The connecting rod is shown in FIGS. In general, the single rod 300 is configured such that a larger (crank side) end portion 302 is connected to a smaller (piston side) end portion 304 via a body portion 306. Piston end 304 includes a small hole or eye 308 that is configured to receive a wrist pin. The crank end 302 includes a large hole or eye 310 made to receive the shaft portion of the crankshaft. Conveniently, the body 306, the crank end 302 and the piston end 304 are made of a first alloy such as steel or aluminum alloy.

  A crank support surface 316 is formed at the crank side end portion 302. The crank support surface 316 is molded as a single body or integrally with the body 306 and the ends 302, 304 as part of a single molding process. The crank support surface 316 engages with a crank pin (not shown). A wrist pin support surface 318 is formed at the piston side end portion 304. The wrist pin support surface 318 is also formed as a single body or integrally with the body portion 306 and the end portions 302 and 304. The wrist pin support surface 318 engages with a wrist pin (not shown). The support surfaces 316 and 318 are made of an alloy different from that of the body 306 and the remaining portions of the end portions 302 and 304, such as bronze. The crank support surface 316 is conveniently formed on the edge 312 of the inner layer that forms the opening of the large eye 310. The wrist pin support surface 318 is advantageously formed on the edge 314 of the inner layer that forms the opening of the small eye 308. In order to give the crank support surface 316 and wrist pin support surface 318 different properties such as strength, friction, etc., the crank support surface 316 is formed from one alloy and the wrist pin support surface 318 is formed from another alloy. Is convenient. The two alloys are advantageously different from the material comprising the bulk of the barrel 306, crank end 302, and piston end 304. As will be appreciated by those skilled in the art, other alloys may be used without departing from the scope of the present invention.

  FIG. 13 shows an alternative apparatus for forming green parts according to the method of FIG. The feed shoe device according to this embodiment includes a single container 222. The container 222 includes a side wall 223 and a central partition 224. Side wall 223 and central partition 224 define a first compartment or chamber 226 and a second compartment or chamber 228. The first compartment 226 receives the first metal powder from the first hopper 230 and the second compartment 228 receives the second metal powder from the second hopper 232. The first chamber 226 is provided with a first powder outlet 234, and the second chamber 228 is provided with a twenty-second powder outlet 226.

  In operation, the first and second powders are simultaneously supplied to the mold cavity. Each powder outlet 234, 236 is sized and sized to facilitate filling of each desired location in cavity 238 with the first and second powders prior to the pressing process. Instead, the first outlet 234 or the second outlet 236 may be placed on the mold cavity 238 by moving the container 222 in a linear direction with the piston 240 before filling each metal powder. Good. In yet another approach, the powder outlets 234, 235 may be selectively opened and closed to create a density gradient in the part, or a second material may be placed in the first material. Moreover, you may employ | adopt what combined said each method as a part of the same shaping | molding process.

  FIG. 14 shows another embodiment of a green part forming (feed shoe) apparatus 250. This embodiment also includes a single container 252. The container includes a first partition 256 and a second partition 254, and defines a first chamber or compartment 258, a second chamber 260, and a third chamber 262. Each chamber 258, 260, 262 receives a first powder outlet 264, a second powder outlet 266, and a third powder outlet 268, respectively, and communicates with the first hopper 270, the second hopper 272, and the third hopper 274, respectively. ing. As will be appreciated by those skilled in the art, the present invention may be practiced with more than three chambers without departing from the scope of the present invention. Furthermore, one hopper may communicate with two or more chambers.

  Using three chambers 258, 260, 262 allows the first powder of two different powders to be introduced simultaneously into two locations of the mold cavity 276. Alternatively, the three chambers 258, 260, 262 allow three powders to be introduced into the mold cavity 276 as part of a single molding process. The embodiment of FIG. 14 is implemented in substantially the same manner as described above for the two-chamber embodiment.

  The above procedure is performed to provide components with different characteristics at separate locations on the part. For example, the connecting rod of an internal combustion engine is provided with an integral bearing or support surface in a single molding process. In the present method for manufacturing a connecting rod, an additional step of separately molding and attaching a separate bearing and bushing to the rod is not required, and the cost, time, number of parts, and complexity can be reduced.

  As described above, the present invention has been described with reference to the above-described embodiments. However, as can be understood by those skilled in the art, changes can be made to the embodiments and details without departing from the spirit and scope of the present invention. The described embodiments are intended to be illustrative in all respects and are not intended to limit the invention. Therefore, the scope of the present invention is expressed not by the contents of the above description but by the claims.

It is a process flowchart which shows the powder metallurgy manufacturing process by a prior art. 1 is a partially broken perspective view of a vehicle engine according to the prior art. It is a top view of the connecting rod by a prior art. It is sectional drawing which follows the aa line of the connecting rod of FIG. 1 is a perspective view of a connecting rod according to the prior art. 4 is a process flow chart for fabricating a heterogeneous component using a powder metallurgy manufacturing process according to the present invention. 1 is a side cutaway view of a green part molding apparatus according to the present invention. 1 is a front view of a green part molding apparatus according to the present invention. It is a top view of the green component forming apparatus by this invention. It is a partial upper surface fracture | rupture detailed drawing of the supply valve of the raw component molding apparatus by this invention. FIG. 3 is a partially broken side detail view of a powder outlet in an open position according to the present invention. FIG. 3 is a partial cutaway side detail view of the powder outlet in the closed position according to the present invention. 1 is a side cutaway view of a green part molding apparatus according to the present invention. 1 is a side cutaway view of a green part molding apparatus according to the present invention. 1 is a side cutaway view of a non-homogeneous connecting rod according to the present invention. It is a front view of the connecting rod of FIG.

Claims (3)

A connecting rod comprising a non-homogeneous structure formed into a single body by a powder metallurgy process,
The structure has a piston side end, a crankshaft side end, and an interconnecting body,
The piston side end, the crankshaft side end, and the interconnection body are formed of a structural material,
The piston end has a small eye for receiving a wrist pin;
The small eye comprises a second material molded integrally with the structural material ;
The crankshaft side end has a large eye for receiving a crankpin, and the large eye includes a third material molded integrally with the structural material forming process,
The connecting rod, wherein the second material and the third material are different powder metals . A method of forming a connecting rod,
Performing a powder metallurgy process on at least three different metal components to form a heterogeneous connecting rod ;
Integrally forming at least a portion of a small eye support surface that is engageable with a wrist pin by a first component of the at least three different metal components;
Integrally forming at least a portion of a large eye support surface engageable with a crankpin by a second component of the at least three different metal components;
Forming a piston side end, a crankshaft side end, and an interconnecting body integrally with a third component of the at least three different metal components,
The second component and the third component of the at least three different metal components are different metal components,
A method of forming a connecting rod. Filling the first part of the mold with the first metal powder;
Filling the second part of the mold with the second metal powder ;
Filling the third part of the mold with the third metal powder;
Applying pressure to the metal powder in the mold;
Sintering the metal powder in the mold.
The method of claim 2 .

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